In the past, a framework of "Impreg Mahogany" was created. Impreg mahogany is laminated strips of mahogany bonded with resins which are considered to be carcinogenic. The framework consisted of platforms and support structures that provide attachment surfaces for "armatures". Armatures are tooling bases, again normally made of impreg mahogany, to provide customized support bridging the space between the support structure attachment surfaces of the framework and the finished product surface development. By nature of their design, the armature also provided machining base coordinates for use in manufacturing processes such as Numeric Controlled (NC) machining, and Coordinate Measuring Machines (CMM) inspection.
Impreg mahogany is a German-made product which is carcinogenic. It is now in limited supply, is very expensive and requires toxic waste disposal. In the normal operating methods used with the impreg mahogany product, dimensional accuracy was suspect due to changes in temperature and humidity. In addition, the normal material handling, shipping and storage of the wood base system is more vulnerable to damage. When the design verification process for a particular model year was complete, the wood based system was scrapped.
Before an industry acknowledgement for increased quality, impreg mahogany structures had performed satisfactorily. With the advanced use of Computer Aided Design (CAD), it became apparent when a verification model was considered acceptable, it could be scanned or digitized to actual acceptable surface. The math data from the scanning process would then be fed back into the computer as qualified data. Numerical control (NC) surfacing and cutter path programming would allow product steel dies to be cut. This process reduces the manufacturing process by a time period of about one year. It also minimizes variables associated with previous manufacturing methods.
To ensure the accuracy of the verification model, a more accurate support structure had to be found. Many methods were investigated. The most popular was an extruded aluminum structure fabricated of a product named "Item". This product was widely used, but did not satisfy all the performance requirements.
Various types of other modular tooling systems for models has been proposed. For example, U.S. Pat. No. 5,106,290 discloses a tool system for an integrated manufacturing and assembly system that includes a plurality of profile boards which are connected together with connector boards. The profile board includes a profile edge which defines a mold line surface. U.S. Pat. No. 4,695,032 discloses a convertible mold having a frame including bars and beams carrying movable heads that support a lattice of slats in a desired configuration. A conforming sheet material is fixed to the slats to provide a mold surface. Universal fixtures have also been disclosed for Coordinate Measuring Machines (CMM) as can be seen for example in U.S. Pat. No. 5,107,599 and U.S. Pat. No. 5,026,033.